Willis Issues Report on Seismic Hazard in United States

-- Preparing for a New View of U.S. Earthquake Risk --

London, UK, October 17, 2008 – Willis Group Holdings (NYSE: WSH), the global
insurance broker, has released a report summarizing recent changes in the scientific
view of seismic hazard in the United States. The report has gained significant market
recognition, including being added to the curriculum of the Associate in Reinsurance
(ARe) designation program, offered by both the American Institute for Chartered
Property Casualty Underwriters and the Insurance Institute of America.

The report provides detailed regional maps illustrating the results of two recent
academic research papers: the 2008 National Seismic Hazard Maps and the 2007
Uniform California Earthquake Rupture Forecast. It focuses on the implication these
new studies could have on catastrophe risk managers, including a discussion of how
the vendor earthquake catastrophe models may change in the U.S. as a result.

“This report lays the ground work for understanding the new scientific view of
earthquake risk in the U.S.,” noted Julie Serakos, EVP, Willis Catastrophe
Management Services. “We are pleased to publish this report as it serves as the
starting point for assisting insurers with making appropriate decisions to manage their
earthquake risk going forward.”

The three key themes discussed in Willis’ report are:

The greatest magnitude changes in seismic risk have occurred in California,
with significant but lesser changes in the Pacific Northwest.

Measurements from recent large earthquakes around the world indicate that
tall buildings in California may experience less shaking in a large earthquake
than was previously assumed.

The vendors’ U.S. earthquake catastrophe models will be recalibrated and
therefore the seismic hazard changes presented in this report may be offset
or amplified by changes to other modelling components.

“Risk managers and insurance executives are confronted by an array of obstacles
when understanding the current scientific view of seismic hazard,” said Kyle Beatty,
Vice President, Willis Catastrophe Management Services. “We expect this report,
and others to follow, will help them formulate a more comprehensive picture of the
key issues at hand.”

Willis Group Holdings Limited is a leading global insurance broker, developing and
delivering professional insurance, reinsurance, risk management, financial and
human resource consulting and actuarial services to corporations, public entities and
institutions around the world. Willis has more than 400 offices in nearly 120
countries, with a global team of approximately 20,000 Associates serving clients in
some 190 countries. Additional information on Willis may be found at
www.willis.com.